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<body class="manpage">
<div id="header">
<h1>
zmq_setsockopt(3) Manual Page
</h1>
<h2>NAME</h2>
<div class="sectionbody">
<p>zmq_setsockopt -
   set 0MQ socket options
</p>
</div>
</div>
<div id="content">
<div class="sect1">
<h2 id="_synopsis">SYNOPSIS</h2>
<div class="sectionbody">
<div class="paragraph"><p><strong>int zmq_setsockopt (void <em>*socket</em>, int <em>option_name</em>, const void <em>*option_value</em>, size_t <em>option_len</em>);</strong></p></div>
<div class="paragraph"><p>Caution: All options, with the exception of ZMQ_SUBSCRIBE, ZMQ_UNSUBSCRIBE,
ZMQ_LINGER, ZMQ_ROUTER_HANDOVER, ZMQ_ROUTER_MANDATORY, ZMQ_PROBE_ROUTER,
ZMQ_XPUB_VERBOSE, ZMQ_XPUB_VERBOSER, ZMQ_REQ_CORRELATE,
ZMQ_REQ_RELAXED, ZMQ_SNDHWM and ZMQ_RCVHWM, only take effect for
subsequent socket bind/connects.</p></div>
<div class="paragraph"><p>Specifically, security options take effect for subsequent bind/connect calls,
and can be changed at any time to affect subsequent binds and/or connects.</p></div>
</div>
</div>
<div class="sect1">
<h2 id="_description">DESCRIPTION</h2>
<div class="sectionbody">
<div class="paragraph"><p>The <em>zmq_setsockopt()</em> function shall set the option specified by the
<em>option_name</em> argument to the value pointed to by the <em>option_value</em> argument
for the ØMQ socket pointed to by the <em>socket</em> argument. The <em>option_len</em>
argument is the size of the option value in bytes. For options taking a value of
type "character string", the provided byte data should either contain no zero
bytes, or end in a single zero byte (terminating ASCII NUL character).</p></div>
<div class="paragraph"><p>The following socket options can be set with the <em>zmq_setsockopt()</em> function:</p></div>
<div class="sect2">
<h3 id="_zmq_affinity_set_i_o_thread_affinity">ZMQ_AFFINITY: Set I/O thread affinity</h3>
<div class="paragraph"><p>The <em>ZMQ_AFFINITY</em> option shall set the I/O thread affinity for newly created
connections on the specified <em>socket</em>.</p></div>
<div class="paragraph"><p>Affinity determines which threads from the ØMQ I/O thread pool associated with
the socket&#8217;s <em>context</em> shall handle newly created connections.  A value of zero
specifies no affinity, meaning that work shall be distributed fairly among all
ØMQ I/O threads in the thread pool. For non-zero values, the lowest bit
corresponds to thread 1, second lowest bit to thread 2 and so on.  For example,
a value of 3 specifies that subsequent connections on <em>socket</em> shall be handled
exclusively by I/O threads 1 and 2.</p></div>
<div class="paragraph"><p>See also <a href="zmq_init.html">zmq_init(3)</a> for details on allocating the number of I/O
threads for a specific <em>context</em>.</p></div>
<div class="hdlist"><table>
<tr>
<td class="hdlist1">
Option value type
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
uint64_t
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Option value unit
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
N/A (bitmap)
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Default value
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
0
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Applicable socket types
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
N/A
</p>
</td>
</tr>
</table></div>
</div>
<div class="sect2">
<h3 id="_zmq_backlog_set_maximum_length_of_the_queue_of_outstanding_connections">ZMQ_BACKLOG: Set maximum length of the queue of outstanding connections</h3>
<div class="paragraph"><p>The <em>ZMQ_BACKLOG</em> option shall set the maximum length of the queue of
outstanding peer connections for the specified <em>socket</em>; this only applies to
connection-oriented transports. For details refer to your operating system
documentation for the <em>listen</em> function.</p></div>
<div class="hdlist"><table>
<tr>
<td class="hdlist1">
Option value type
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
int
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Option value unit
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
connections
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Default value
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
100
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Applicable socket types
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
all, only for connection-oriented transports.
</p>
</td>
</tr>
</table></div>
</div>
<div class="sect2">
<h3 id="_zmq_bindtodevice_set_name_of_device_to_bind_the_socket_to">ZMQ_BINDTODEVICE: Set name of device to bind the socket to</h3>
<div class="paragraph"><p>The <em>ZMQ_BINDTODEVICE</em> option binds this socket to a particular device, eg.
an interface or VRF. If a socket is bound to an interface, only packets
received from that particular interface are processed by the socket. If device
is a VRF device, then subsequent binds/connects to that socket use addresses
in the VRF routing table.</p></div>
<div class="admonitionblock">
<table><tr>
<td class="icon">
<div class="title">Note</div>
</td>
<td class="content">requires setting CAP_NET_RAW on the compiled program.</td>
</tr></table>
</div>
<div class="hdlist"><table>
<tr>
<td class="hdlist1">
Option value type
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
character string
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Option value unit
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
N/A
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Default value
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
not set
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Applicable socket types
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
all, when using TCP or UDP transports.
</p>
</td>
</tr>
</table></div>
</div>
<div class="sect2">
<h3 id="_zmq_connect_rid_assign_the_next_outbound_connection_id">ZMQ_CONNECT_RID: Assign the next outbound connection id</h3>
<div class="paragraph"><p>This option name is now deprecated. Use ZMQ_CONNECT_ROUTING_ID instead.
ZMQ_CONNECT_RID remains as an alias for now.</p></div>
</div>
<div class="sect2">
<h3 id="_zmq_connect_routing_id_assign_the_next_outbound_routing_id">ZMQ_CONNECT_ROUTING_ID: Assign the next outbound routing id</h3>
<div class="paragraph"><p>The <em>ZMQ_CONNECT_ROUTING_ID</em> option sets the peer id of the peer connected
via the next zmq_connect() call, such that that connection is immediately ready for
data transfer with the given routing id.  This option applies only to the first
subsequent call to zmq_connect(), zmq_connect() calls thereafter use the default
connection behaviour.</p></div>
<div class="paragraph"><p>Typical use is to set this socket option ahead of each zmq_connect() call.
Each connection MUST be assigned a unique routing id. Assigning a
routing id that is already in use is not allowed.</p></div>
<div class="paragraph"><p>Useful when connecting ROUTER to ROUTER, or STREAM to STREAM, as it
allows for immediate sending to peers. Outbound routing id framing requirements
for ROUTER and STREAM sockets apply.</p></div>
<div class="paragraph"><p>The routing id must be from 1 to 255 bytes long and MAY NOT start with
a zero byte (such routing ids are reserved for internal use by the ØMQ
infrastructure).</p></div>
<div class="hdlist"><table>
<tr>
<td class="hdlist1">
Option value type
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
binary data
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Option value unit
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
N/A
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Default value
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
NULL
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Applicable socket types
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
ZMQ_ROUTER, ZMQ_STREAM
</p>
</td>
</tr>
</table></div>
</div>
<div class="sect2">
<h3 id="_zmq_conflate_keep_only_last_message">ZMQ_CONFLATE: Keep only last message</h3>
<div class="paragraph"><p>If set, a socket shall keep only one message in its inbound/outbound
queue, this message being the last message received/the last message
to be sent. Ignores <em>ZMQ_RCVHWM</em> and <em>ZMQ_SNDHWM</em> options. Does not
support multi-part messages, in particular, only one part of it is kept
in the socket internal queue.</p></div>
<div class="admonitionblock">
<table><tr>
<td class="icon">
<div class="title">Note</div>
</td>
<td class="content">If recv is not called on the inbound socket, the queue and memory will
grow with each message received. Use <a href="zmq_getsockopt.html">zmq_getsockopt(3)</a> with ZMQ_EVENTS
to trigger the conflation of the messages.</td>
</tr></table>
</div>
<div class="hdlist"><table>
<tr>
<td class="hdlist1">
Option value type
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
int
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Option value unit
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
boolean
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Default value
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
0 (false)
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Applicable socket types
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
ZMQ_PULL, ZMQ_PUSH, ZMQ_SUB, ZMQ_PUB, ZMQ_DEALER
</p>
</td>
</tr>
</table></div>
</div>
<div class="sect2">
<h3 id="_zmq_connect_timeout_set_connect_timeout">ZMQ_CONNECT_TIMEOUT: Set connect() timeout</h3>
<div class="paragraph"><p>Sets how long to wait before timing-out a connect() system call.
The connect() system call normally takes a long time before it returns a
time out error. Setting this option allows the library to time out the call
at an earlier interval.</p></div>
<div class="hdlist"><table>
<tr>
<td class="hdlist1">
Option value type
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
int
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Option value unit
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
milliseconds
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Default value
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
0 (disabled)
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Applicable socket types
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
all, when using TCP transports.
</p>
</td>
</tr>
</table></div>
</div>
<div class="sect2">
<h3 id="_zmq_curve_publickey_set_curve_public_key">ZMQ_CURVE_PUBLICKEY: Set CURVE public key</h3>
<div class="paragraph"><p>Sets the socket&#8217;s long term public key. You must set this on CURVE client
sockets, see <a href="zmq_curve.html">zmq_curve(7)</a>. You can provide the key as 32 binary
bytes, or as a 40-character string encoded in the Z85 encoding format and
terminated in a null byte. The public key must always be used with the
matching secret key. To generate a public/secret key pair, use
<a href="zmq_curve_keypair.html">zmq_curve_keypair(3)</a>. To derive the public key from a secret key,
use <a href="zmq_curve_public.html">zmq_curve_public(3)</a>.</p></div>
<div class="admonitionblock">
<table><tr>
<td class="icon">
<div class="title">Note</div>
</td>
<td class="content">an option value size of 40 is supported for backwards compatibility,
though is deprecated.</td>
</tr></table>
</div>
<div class="hdlist"><table>
<tr>
<td class="hdlist1">
Option value type
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
binary data or Z85 text string
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Option value size
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
32 or 41
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Default value
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
NULL
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Applicable socket types
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
all, when using TCP transport
</p>
</td>
</tr>
</table></div>
</div>
<div class="sect2">
<h3 id="_zmq_curve_secretkey_set_curve_secret_key">ZMQ_CURVE_SECRETKEY: Set CURVE secret key</h3>
<div class="paragraph"><p>Sets the socket&#8217;s long term secret key. You must set this on both CURVE
client and server sockets, see <a href="zmq_curve.html">zmq_curve(7)</a>. You can provide the
key as 32 binary bytes, or as a 40-character string encoded in the Z85
encoding format and terminated in a null byte. To generate a public/secret
key pair, use <a href="zmq_curve_keypair.html">zmq_curve_keypair(3)</a>. To derive the public key from
a secret key, use <a href="zmq_curve_public.html">zmq_curve_public(3)</a>.</p></div>
<div class="admonitionblock">
<table><tr>
<td class="icon">
<div class="title">Note</div>
</td>
<td class="content">an option value size of 40 is supported for backwards compatibility,
though is deprecated.</td>
</tr></table>
</div>
<div class="hdlist"><table>
<tr>
<td class="hdlist1">
Option value type
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
binary data or Z85 text string
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Option value size
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
32 or 41
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Default value
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
NULL
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Applicable socket types
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
all, when using TCP transport
</p>
</td>
</tr>
</table></div>
</div>
<div class="sect2">
<h3 id="_zmq_curve_server_set_curve_server_role">ZMQ_CURVE_SERVER: Set CURVE server role</h3>
<div class="paragraph"><p>Defines whether the socket will act as server for CURVE security, see
<a href="zmq_curve.html">zmq_curve(7)</a>. A value of <em>1</em> means the socket will act as
CURVE server. A value of <em>0</em> means the socket will not act as CURVE
server, and its security role then depends on other option settings.
Setting this to <em>0</em> shall reset the socket security to NULL. When you
set this you must also set the server&#8217;s secret key using the
ZMQ_CURVE_SECRETKEY option. A server socket does not need to know
its own public key.</p></div>
<div class="hdlist"><table>
<tr>
<td class="hdlist1">
Option value type
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
int
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Option value unit
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
0, 1
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Default value
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
0
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Applicable socket types
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
all, when using TCP transport
</p>
</td>
</tr>
</table></div>
</div>
<div class="sect2">
<h3 id="_zmq_curve_serverkey_set_curve_server_key">ZMQ_CURVE_SERVERKEY: Set CURVE server key</h3>
<div class="paragraph"><p>Sets the socket&#8217;s long term server key. You must set this on CURVE client
sockets, see <a href="zmq_curve.html">zmq_curve(7)</a>. You can provide the key as 32 binary
bytes, or as a 40-character string encoded in the Z85 encoding format and
terminated in a null byte. This key must have been generated together with
the server&#8217;s secret key. To generate a public/secret key pair, use
<a href="zmq_curve_keypair.html">zmq_curve_keypair(3)</a>.</p></div>
<div class="admonitionblock">
<table><tr>
<td class="icon">
<div class="title">Note</div>
</td>
<td class="content">an option value size of 40 is supported for backwards compatibility,
though is deprecated.</td>
</tr></table>
</div>
<div class="hdlist"><table>
<tr>
<td class="hdlist1">
Option value type
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
binary data or Z85 text string
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Option value size
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
32 or 41
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Default value
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
NULL
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Applicable socket types
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
all, when using TCP transport
</p>
</td>
</tr>
</table></div>
</div>
<div class="sect2">
<h3 id="_zmq_gssapi_plaintext_disable_gssapi_encryption">ZMQ_GSSAPI_PLAINTEXT: Disable GSSAPI encryption</h3>
<div class="paragraph"><p>Defines whether communications on the socket will be encrypted, see
<a href="zmq_gssapi.html">zmq_gssapi(7)</a>. A value of <em>1</em> means  that communications will be
plaintext.  A value of <em>0</em> means communications will be encrypted.</p></div>
<div class="hdlist"><table>
<tr>
<td class="hdlist1">
Option value type
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
int
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Option value unit
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
0, 1
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Default value
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
0 (false)
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Applicable socket types
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
all, when using TCP transport
</p>
</td>
</tr>
</table></div>
</div>
<div class="sect2">
<h3 id="_zmq_gssapi_principal_set_name_of_gssapi_principal">ZMQ_GSSAPI_PRINCIPAL: Set name of GSSAPI principal</h3>
<div class="paragraph"><p>Sets the name of the principal for whom GSSAPI credentials should be acquired.</p></div>
<div class="hdlist"><table>
<tr>
<td class="hdlist1">
Option value type
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
character string
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Option value unit
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
N/A
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Default value
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
not set
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Applicable socket types
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
all, when using TCP transport
</p>
</td>
</tr>
</table></div>
</div>
<div class="sect2">
<h3 id="_zmq_gssapi_server_set_gssapi_server_role">ZMQ_GSSAPI_SERVER: Set GSSAPI server role</h3>
<div class="paragraph"><p>Defines whether the socket will act as server for GSSAPI security, see
<a href="zmq_gssapi.html">zmq_gssapi(7)</a>. A value of <em>1</em> means the socket will act as GSSAPI
server. A value of <em>0</em> means the socket will act as GSSAPI client.</p></div>
<div class="hdlist"><table>
<tr>
<td class="hdlist1">
Option value type
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
int
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Option value unit
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
0, 1
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Default value
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
0 (false)
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Applicable socket types
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
all, when using TCP transport
</p>
</td>
</tr>
</table></div>
</div>
<div class="sect2">
<h3 id="_zmq_gssapi_service_principal_set_name_of_gssapi_service_principal">ZMQ_GSSAPI_SERVICE_PRINCIPAL: Set name of GSSAPI service principal</h3>
<div class="paragraph"><p>Sets the name of the principal of the GSSAPI server to which a GSSAPI client
intends to connect.</p></div>
<div class="hdlist"><table>
<tr>
<td class="hdlist1">
Option value type
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
character string
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Option value unit
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
N/A
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Default value
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
not set
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Applicable socket types
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
all, when using TCP transport
</p>
</td>
</tr>
</table></div>
</div>
<div class="sect2">
<h3 id="_zmq_gssapi_service_principal_nametype_set_name_type_of_service_principal">ZMQ_GSSAPI_SERVICE_PRINCIPAL_NAMETYPE: Set name type of service principal</h3>
<div class="paragraph"><p>Sets the name type of the GSSAPI service principal.  A value of
<em>ZMQ_GSSAPI_NT_HOSTBASED</em> (0) means the name specified with
<em>ZMQ_GSSAPI_SERVICE_PRINCIPAL</em> is interpreted as a host based name.  A value
of <em>ZMQ_GSSAPI_NT_USER_NAME</em> (1) means it is interpreted as a local user name.
A value of <em>ZMQ_GSSAPI_NT_KRB5_PRINCIPAL</em> (2) means it is interpreted as an
unparsed principal name string (valid only with the krb5 GSSAPI mechanism).</p></div>
<div class="hdlist"><table>
<tr>
<td class="hdlist1">
Option value type
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
int
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Option value unit
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
0, 1, 2
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Default value
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
0 (ZMQ_GSSAPI_NT_HOSTBASED)
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Applicable socket types
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
all, when using TCP or IPC transport
</p>
</td>
</tr>
</table></div>
</div>
<div class="sect2">
<h3 id="_zmq_gssapi_principal_nametype_set_name_type_of_principal">ZMQ_GSSAPI_PRINCIPAL_NAMETYPE: Set name type of principal</h3>
<div class="paragraph"><p>Sets the name type of the GSSAPI principal.  A value of
<em>ZMQ_GSSAPI_NT_HOSTBASED</em> (0) means the name specified with
<em>ZMQ_GSSAPI_PRINCIPAL</em> is interpreted as a host based name.  A value of
<em>ZMQ_GSSAPI_NT_USER_NAME</em> (1) means it is interpreted as a local user name.
A value of <em>ZMQ_GSSAPI_NT_KRB5_PRINCIPAL</em> (2) means it is interpreted as an
unparsed principal name string (valid only with the krb5 GSSAPI mechanism).</p></div>
<div class="hdlist"><table>
<tr>
<td class="hdlist1">
Option value type
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
int
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Option value unit
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
0, 1, 2
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Default value
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
0 (ZMQ_GSSAPI_NT_HOSTBASED)
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Applicable socket types
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
all, when using TCP or IPC transport
</p>
</td>
</tr>
</table></div>
</div>
<div class="sect2">
<h3 id="_zmq_handshake_ivl_set_maximum_handshake_interval">ZMQ_HANDSHAKE_IVL: Set maximum handshake interval</h3>
<div class="paragraph"><p>The <em>ZMQ_HANDSHAKE_IVL</em> option shall set the maximum handshake interval for
the specified <em>socket</em>. Handshaking is the exchange of socket configuration
information (socket type, routing id, security) that occurs when a connection
is first opened, only for connection-oriented transports. If handshaking does
not complete within the configured time, the connection shall be closed.
The value 0 means no handshake time limit.</p></div>
<div class="hdlist"><table>
<tr>
<td class="hdlist1">
Option value type
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
int
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Option value unit
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
milliseconds
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Default value
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
30000
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Applicable socket types
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
all but ZMQ_STREAM, only for connection-oriented transports
</p>
</td>
</tr>
</table></div>
</div>
<div class="sect2">
<h3 id="_zmq_heartbeat_ivl_set_interval_between_sending_zmtp_heartbeats">ZMQ_HEARTBEAT_IVL: Set interval between sending ZMTP heartbeats</h3>
<div class="paragraph"><p>The <em>ZMQ_HEARTBEAT_IVL</em> option shall set the interval between sending ZMTP heartbeats
for the specified <em>socket</em>. If this option is set and is greater than 0, then a <em>PING</em>
ZMTP command will be sent every <em>ZMQ_HEARTBEAT_IVL</em> milliseconds.</p></div>
<div class="hdlist"><table>
<tr>
<td class="hdlist1">
Option value type
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
int
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Option value unit
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
milliseconds
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Default value
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
0
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Applicable socket types
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
all, when using connection-oriented transports
</p>
</td>
</tr>
</table></div>
</div>
<div class="sect2">
<h3 id="_zmq_heartbeat_timeout_set_timeout_for_zmtp_heartbeats">ZMQ_HEARTBEAT_TIMEOUT: Set timeout for ZMTP heartbeats</h3>
<div class="paragraph"><p>The <em>ZMQ_HEARTBEAT_TIMEOUT</em> option shall set how long to wait before timing-out a
connection after sending a <em>PING</em> ZMTP command and not receiving any traffic. This
option is only valid if <em>ZMQ_HEARTBEAT_IVL</em> is also set, and is greater than 0. The
connection will time out if there is no traffic received after sending the <em>PING</em>
command, but the received traffic does not have to be a <em>PONG</em> command - any received
traffic will cancel the timeout.</p></div>
<div class="hdlist"><table>
<tr>
<td class="hdlist1">
Option value type
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
int
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Option value unit
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
milliseconds
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Default value
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
0 normally, ZMQ_HEARTBEAT_IVL if it is set
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Applicable socket types
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
all, when using connection-oriented transports
</p>
</td>
</tr>
</table></div>
</div>
<div class="sect2">
<h3 id="_zmq_heartbeat_ttl_set_the_ttl_value_for_zmtp_heartbeats">ZMQ_HEARTBEAT_TTL: Set the TTL value for ZMTP heartbeats</h3>
<div class="paragraph"><p>The <em>ZMQ_HEARTBEAT_TTL</em> option shall set the timeout on the remote peer for ZMTP
heartbeats. If this option is greater than 0, the remote side shall time out the
connection if it does not receive any more traffic within the TTL period. This option
does not have any effect if <em>ZMQ_HEARTBEAT_IVL</em> is not set or is 0. Internally, this
value is rounded down to the nearest decisecond, any value less than 100 will have
no effect.</p></div>
<div class="hdlist"><table>
<tr>
<td class="hdlist1">
Option value type
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
int
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Option value unit
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
milliseconds
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Default value
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
0
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Maximum value
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
6553599 (which is 2^16-1 deciseconds)
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Applicable socket types
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
all, when using connection-oriented transports
</p>
</td>
</tr>
</table></div>
</div>
<div class="sect2">
<h3 id="_zmq_identity_set_socket_identity">ZMQ_IDENTITY: Set socket identity</h3>
<div class="paragraph"><p>This option name is now deprecated. Use ZMQ_ROUTING_ID instead.
ZMQ_IDENTITY remains as an alias for now.</p></div>
</div>
<div class="sect2">
<h3 id="_zmq_immediate_queue_messages_only_to_completed_connections">ZMQ_IMMEDIATE: Queue messages only to completed connections</h3>
<div class="paragraph"><p>By default queues will fill on outgoing connections even if the connection has
not completed. This can lead to "lost" messages on sockets with round-robin
routing (REQ, PUSH, DEALER). If this option is set to <code>1</code>, messages shall be
queued only to completed connections. This will cause the socket to block if
there are no other connections, but will prevent queues from filling on pipes
awaiting connection.</p></div>
<div class="hdlist"><table>
<tr>
<td class="hdlist1">
Option value type
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
int
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Option value unit
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
boolean
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Default value
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
0 (false)
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Applicable socket types
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
all, only for connection-oriented transports.
</p>
</td>
</tr>
</table></div>
</div>
<div class="sect2">
<h3 id="_zmq_invert_matching_invert_message_filtering">ZMQ_INVERT_MATCHING: Invert message filtering</h3>
<div class="paragraph"><p>Reverses the filtering behavior of PUB-SUB sockets, when set to 1.</p></div>
<div class="paragraph"><p>On <em>PUB</em> and <em>XPUB</em> sockets, this causes messages to be sent to all
connected sockets <em>except</em> those subscribed to a prefix that matches
the message. On <em>SUB</em> sockets, this causes only incoming messages that
do <em>not</em> match any of the socket&#8217;s subscriptions to be received by the user.</p></div>
<div class="paragraph"><p>Whenever <em>ZMQ_INVERT_MATCHING</em> is set to 1 on a <em>PUB</em> socket, all <em>SUB</em>
sockets connecting to it must also have the option set to 1. Failure to
do so will have the <em>SUB</em> sockets reject everything the <em>PUB</em> socket sends
them. <em>XSUB</em> sockets do not need to do this because they do not filter
incoming messages.</p></div>
<div class="hdlist"><table>
<tr>
<td class="hdlist1">
Option value type
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
int
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Option value unit
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
0,1
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Default value
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
0
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Applicable socket types
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
ZMQ_PUB, ZMQ_XPUB, ZMQ_SUB
</p>
</td>
</tr>
</table></div>
</div>
<div class="sect2">
<h3 id="_zmq_ipv6_enable_ipv6_on_socket">ZMQ_IPV6: Enable IPv6 on socket</h3>
<div class="paragraph"><p>Set the IPv6 option for the socket. A value of <code>1</code> means IPv6 is
enabled on the socket, while <code>0</code> means the socket will use only IPv4.
When IPv6 is enabled the socket will connect to, or accept connections
from, both IPv4 and IPv6 hosts.</p></div>
<div class="hdlist"><table>
<tr>
<td class="hdlist1">
Option value type
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
int
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Option value unit
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
boolean
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Default value
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
0 (false)
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Applicable socket types
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
all, when using TCP transports.
</p>
</td>
</tr>
</table></div>
</div>
<div class="sect2">
<h3 id="_zmq_linger_set_linger_period_for_socket_shutdown">ZMQ_LINGER: Set linger period for socket shutdown</h3>
<div class="paragraph"><p>The <em>ZMQ_LINGER</em> option shall set the linger period for the specified <em>socket</em>.
The linger period determines how long pending messages which have yet to be
sent to a peer shall linger in memory after a socket is disconnected with
<a href="zmq_disconnect.html">zmq_disconnect(3)</a> or closed with <a href="zmq_close.html">zmq_close(3)</a>, and further
affects the termination of the socket&#8217;s context with <a href="zmq_ctx_term.html">zmq_ctx_term(3)</a>.
The following outlines the different behaviours:</p></div>
<div class="ulist"><ul>
<li>
<p>
A value of <em>-1</em> specifies an infinite linger period. Pending
  messages shall not be discarded after a call to <em>zmq_disconnect()</em> or
  <em>zmq_close()</em>; attempting to terminate the socket&#8217;s context with <em>zmq_ctx_term()</em>
  shall block until all pending messages have been sent to a peer.
</p>
</li>
<li>
<p>
The value of <em>0</em> specifies no linger period. Pending messages shall be
  discarded immediately after a call to <em>zmq_disconnect()</em> or <em>zmq_close()</em>.
</p>
</li>
<li>
<p>
Positive values specify an upper bound for the linger period in milliseconds.
  Pending messages shall not be discarded after a call to <em>zmq_disconnect()</em> or
  <em>zmq_close()</em>; attempting to terminate the socket&#8217;s context with <em>zmq_ctx_term()</em>
  shall block until either all pending messages have been sent to a peer, or the
  linger period expires, after which any pending messages shall be discarded.
</p>
<div class="hdlist"><table>
<tr>
<td class="hdlist1">
Option value type
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
int
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Option value unit
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
milliseconds
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Default value
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
-1 (infinite)
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Applicable socket types
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
all
</p>
</td>
</tr>
</table></div>
</li>
</ul></div>
</div>
<div class="sect2">
<h3 id="_zmq_maxmsgsize_maximum_acceptable_inbound_message_size">ZMQ_MAXMSGSIZE: Maximum acceptable inbound message size</h3>
<div class="paragraph"><p>Limits the size of the inbound message. If a peer sends a message larger than
ZMQ_MAXMSGSIZE it is disconnected. Value of -1 means <em>no limit</em>.</p></div>
<div class="hdlist"><table>
<tr>
<td class="hdlist1">
Option value type
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
int64_t
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Option value unit
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
bytes
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Default value
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
-1
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Applicable socket types
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
all
</p>
</td>
</tr>
</table></div>
</div>
<div class="sect2">
<h3 id="_zmq_metadata_add_application_metadata_properties_to_a_socket">ZMQ_METADATA: Add application metadata properties to a socket</h3>
<div class="paragraph"><p>The <em>ZMQ_METADATA</em> option shall add application metadata to the specified <em>socket</em>,
the metadata is exchanged with peers during connection setup. A metadata property is
specfied as a string, delimited by a colon, starting with the metadata <em>property</em>
followed by the metadata value, for example "X-key:value".
<em>Property</em> names are restrited to maximum 255 characters and must be prefixed by "X-".
Multiple application metadata properties can be added to a socket by executing zmq_setsockopt()
multiple times. As the argument is a null-terminated string, binary data must be encoded
before it is added e.g. using Z85 (<a href="zmq_z85_encode.html">zmq_z85_encode(3)</a>).</p></div>
<div class="admonitionblock">
<table><tr>
<td class="icon">
<div class="title">Note</div>
</td>
<td class="content">in DRAFT state, not yet available in stable releases.</td>
</tr></table>
</div>
<div class="hdlist"><table>
<tr>
<td class="hdlist1">
Option value type
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
character string
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Option value unit
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
N/A
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Default value
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
not set
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Applicable socket types
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
all
</p>
</td>
</tr>
</table></div>
</div>
<div class="sect2">
<h3 id="_zmq_multicast_hops_maximum_network_hops_for_multicast_packets">ZMQ_MULTICAST_HOPS: Maximum network hops for multicast packets</h3>
<div class="paragraph"><p>Sets the time-to-live field in every multicast packet sent from this socket.
The default is 1 which means that the multicast packets don&#8217;t leave the local
network.</p></div>
<div class="hdlist"><table>
<tr>
<td class="hdlist1">
Option value type
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
int
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Option value unit
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
network hops
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Default value
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
1
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Applicable socket types
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
all, when using multicast transports
</p>
</td>
</tr>
</table></div>
</div>
<div class="sect2">
<h3 id="_zmq_multicast_maxtpdu_maximum_transport_data_unit_size_for_multicast_packets">ZMQ_MULTICAST_MAXTPDU: Maximum transport data unit size for multicast packets</h3>
<div class="paragraph"><p>Sets the maximum transport data unit size used for outbound multicast
packets.</p></div>
<div class="paragraph"><p>This must be set at or below the minimum Maximum Transmission Unit (MTU) for
all network paths over which multicast reception is required.</p></div>
<div class="hdlist"><table>
<tr>
<td class="hdlist1">
Option value type
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
int
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Option value unit
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
bytes
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Default value
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
1500
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Applicable socket types
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
all, when using multicast transports
</p>
</td>
</tr>
</table></div>
</div>
<div class="sect2">
<h3 id="_zmq_plain_password_set_plain_security_password">ZMQ_PLAIN_PASSWORD: Set PLAIN security password</h3>
<div class="paragraph"><p>Sets the password for outgoing connections over TCP or IPC. If you set this
to a non-null value, the security mechanism used for connections shall be
PLAIN, see <a href="zmq_plain.html">zmq_plain(7)</a>. If you set this to a null value, the security
mechanism used for connections shall be NULL, see <a href="zmq_null.html">zmq_null(3)</a>.</p></div>
<div class="hdlist"><table>
<tr>
<td class="hdlist1">
Option value type
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
character string
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Option value unit
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
N/A
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Default value
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
not set
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Applicable socket types
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
all, when using TCP transport
</p>
</td>
</tr>
</table></div>
</div>
<div class="sect2">
<h3 id="_zmq_plain_server_set_plain_server_role">ZMQ_PLAIN_SERVER: Set PLAIN server role</h3>
<div class="paragraph"><p>Defines whether the socket will act as server for PLAIN security, see
<a href="zmq_plain.html">zmq_plain(7)</a>. A value of <em>1</em> means the socket will act as
PLAIN server. A value of <em>0</em> means the socket will not act as PLAIN
server, and its security role then depends on other option settings.
Setting this to <em>0</em> shall reset the socket security to NULL.</p></div>
<div class="hdlist"><table>
<tr>
<td class="hdlist1">
Option value type
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
int
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Option value unit
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
0, 1
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Default value
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
0
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Applicable socket types
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
all, when using TCP transport
</p>
</td>
</tr>
</table></div>
</div>
<div class="sect2">
<h3 id="_zmq_plain_username_set_plain_security_username">ZMQ_PLAIN_USERNAME: Set PLAIN security username</h3>
<div class="paragraph"><p>Sets the username for outgoing connections over TCP or IPC. If you set this
to a non-null value, the security mechanism used for connections shall be
PLAIN, see <a href="zmq_plain.html">zmq_plain(7)</a>. If you set this to a null value, the security
mechanism used for connections shall be NULL, see <a href="zmq_null.html">zmq_null(3)</a>.</p></div>
<div class="hdlist"><table>
<tr>
<td class="hdlist1">
Option value type
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
character string
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Option value unit
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
N/A
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Default value
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
not set
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Applicable socket types
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
all, when using TCP transport
</p>
</td>
</tr>
</table></div>
</div>
<div class="sect2">
<h3 id="_zmq_use_fd_set_the_pre_allocated_socket_file_descriptor">ZMQ_USE_FD: Set the pre-allocated socket file descriptor</h3>
<div class="paragraph"><p>When set to a positive integer value before zmq_bind is called on the socket,
the socket shall use the corresponding file descriptor for connections over
TCP or IPC instead of allocating a new file descriptor.
Useful for writing systemd socket activated services. If set to -1 (default),
a new file descriptor will be allocated instead (default behaviour).</p></div>
<div class="admonitionblock">
<table><tr>
<td class="icon">
<div class="title">Note</div>
</td>
<td class="content">if set after calling zmq_bind, this option shall have no effect.
NOTE: the file descriptor passed through MUST have been ran through the "bind"
      and "listen" system calls beforehand. Also, socket option that would
      normally be passed through zmq_setsockopt like TCP buffers length,
      IP_TOS or SO_REUSEADDR MUST be set beforehand by the caller, as they
      must be set before the socket is bound.</td>
</tr></table>
</div>
<div class="hdlist"><table>
<tr>
<td class="hdlist1">
Option value type
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
int
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Option value unit
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
file descriptor
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Default value
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
-1
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Applicable socket types
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
all bound sockets, when using IPC or TCP transport
</p>
</td>
</tr>
</table></div>
</div>
<div class="sect2">
<h3 id="_zmq_probe_router_bootstrap_connections_to_router_sockets">ZMQ_PROBE_ROUTER: bootstrap connections to ROUTER sockets</h3>
<div class="paragraph"><p>When set to 1, the socket will automatically send an empty message when a
new connection is made or accepted. You may set this on REQ, DEALER, or
ROUTER sockets connected to a ROUTER socket. The application must filter
such empty messages. The ZMQ_PROBE_ROUTER option in effect provides the
ROUTER application with an event signaling the arrival of a new peer.</p></div>
<div class="admonitionblock">
<table><tr>
<td class="icon">
<div class="title">Note</div>
</td>
<td class="content">do not set this option on a socket that talks to any other socket
types: the results are undefined.</td>
</tr></table>
</div>
<div class="hdlist"><table>
<tr>
<td class="hdlist1">
Option value type
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
int
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Option value unit
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
0, 1
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Default value
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
0
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Applicable socket types
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
ZMQ_ROUTER, ZMQ_DEALER, ZMQ_REQ
</p>
</td>
</tr>
</table></div>
</div>
<div class="sect2">
<h3 id="_zmq_rate_set_multicast_data_rate">ZMQ_RATE: Set multicast data rate</h3>
<div class="paragraph"><p>The <em>ZMQ_RATE</em> option shall set the maximum send or receive data rate for
multicast transports such as <a href="zmq_pgm.html">zmq_pgm(7)</a> using the specified <em>socket</em>.</p></div>
<div class="hdlist"><table>
<tr>
<td class="hdlist1">
Option value type
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
int
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Option value unit
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
kilobits per second
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Default value
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
100
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Applicable socket types
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
all, when using multicast transports
</p>
</td>
</tr>
</table></div>
</div>
<div class="sect2">
<h3 id="_zmq_rcvbuf_set_kernel_receive_buffer_size">ZMQ_RCVBUF: Set kernel receive buffer size</h3>
<div class="paragraph"><p>The <em>ZMQ_RCVBUF</em> option shall set the underlying kernel receive buffer size for
the <em>socket</em> to the specified size in bytes.  A value of -1 means leave the
OS default unchanged. For details refer to your operating system documentation
for the <em>SO_RCVBUF</em> socket option.</p></div>
<div class="hdlist"><table>
<tr>
<td class="hdlist1">
Option value type
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
int
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Option value unit
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
bytes
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Default value
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
-1
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Applicable socket types
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
all
</p>
</td>
</tr>
</table></div>
</div>
<div class="sect2">
<h3 id="_zmq_rcvhwm_set_high_water_mark_for_inbound_messages">ZMQ_RCVHWM: Set high water mark for inbound messages</h3>
<div class="paragraph"><p>The <em>ZMQ_RCVHWM</em> option shall set the high water mark for inbound messages on
the specified <em>socket</em>. The high water mark is a hard limit on the maximum
number of outstanding messages ØMQ shall queue in memory for any single peer
that the specified <em>socket</em> is communicating with. A value of zero means no
limit.</p></div>
<div class="paragraph"><p>If this limit has been reached the socket shall enter an exceptional state and
depending on the socket type, ØMQ shall take appropriate action such as
blocking or dropping sent messages. Refer to the individual socket descriptions
in <a href="zmq_socket.html">zmq_socket(3)</a> for details on the exact action taken for each socket
type.</p></div>
<div class="admonitionblock">
<table><tr>
<td class="icon">
<div class="title">Note</div>
</td>
<td class="content">ØMQ does not guarantee that the socket will be able to queue as many as ZMQ_RCVHWM
messages, and the actual limit may be lower or higher, depending on socket transport.
A notable example is for sockets using TCP transport; see <a href="zmq_tcp.html">zmq_tcp(7)</a>.</td>
</tr></table>
</div>
<div class="hdlist"><table>
<tr>
<td class="hdlist1">
Option value type
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
int
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Option value unit
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
messages
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Default value
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
1000
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Applicable socket types
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
all
</p>
</td>
</tr>
</table></div>
</div>
<div class="sect2">
<h3 id="_zmq_rcvtimeo_maximum_time_before_a_recv_operation_returns_with_eagain">ZMQ_RCVTIMEO: Maximum time before a recv operation returns with EAGAIN</h3>
<div class="paragraph"><p>Sets the timeout for receive operation on the socket. If the value is <code>0</code>,
<em>zmq_recv(3)</em> will return immediately, with a EAGAIN error if there is no
message to receive. If the value is <code>-1</code>, it will block until a message is
available. For all other values, it will wait for a message for that amount
of time before returning with an EAGAIN error.</p></div>
<div class="hdlist"><table>
<tr>
<td class="hdlist1">
Option value type
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
int
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Option value unit
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
milliseconds
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Default value
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
-1 (infinite)
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Applicable socket types
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
all
</p>
</td>
</tr>
</table></div>
</div>
<div class="sect2">
<h3 id="_zmq_reconnect_ivl_set_reconnection_interval">ZMQ_RECONNECT_IVL: Set reconnection interval</h3>
<div class="paragraph"><p>The <em>ZMQ_RECONNECT_IVL</em> option shall set the initial reconnection interval for
the specified <em>socket</em>.  The reconnection interval is the period ØMQ
shall wait between attempts to reconnect disconnected peers when using
connection-oriented transports. The value -1 means no reconnection.</p></div>
<div class="admonitionblock">
<table><tr>
<td class="icon">
<div class="title">Note</div>
</td>
<td class="content">The reconnection interval may be randomized by ØMQ to prevent
reconnection storms in topologies with a large number of peers per socket.</td>
</tr></table>
</div>
<div class="hdlist"><table>
<tr>
<td class="hdlist1">
Option value type
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
int
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Option value unit
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
milliseconds
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Default value
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
100
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Applicable socket types
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
all, only for connection-oriented transports
</p>
</td>
</tr>
</table></div>
</div>
<div class="sect2">
<h3 id="_zmq_reconnect_ivl_max_set_maximum_reconnection_interval">ZMQ_RECONNECT_IVL_MAX: Set maximum reconnection interval</h3>
<div class="paragraph"><p>The <em>ZMQ_RECONNECT_IVL_MAX</em> option shall set the maximum reconnection interval
for the specified <em>socket</em>.  This is the maximum period ØMQ shall wait between
attempts to reconnect. On each reconnect attempt, the previous interval shall be
doubled untill ZMQ_RECONNECT_IVL_MAX is reached. This allows for exponential
backoff strategy. Default value means no exponential backoff is performed and
reconnect interval calculations are only based on ZMQ_RECONNECT_IVL.</p></div>
<div class="admonitionblock">
<table><tr>
<td class="icon">
<div class="title">Note</div>
</td>
<td class="content">Values less than ZMQ_RECONNECT_IVL will be ignored.</td>
</tr></table>
</div>
<div class="hdlist"><table>
<tr>
<td class="hdlist1">
Option value type
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
int
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Option value unit
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
milliseconds
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Default value
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
0 (only use ZMQ_RECONNECT_IVL)
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Applicable socket types
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
all, only for connection-oriented transports
</p>
</td>
</tr>
</table></div>
</div>
<div class="sect2">
<h3 id="_zmq_recovery_ivl_set_multicast_recovery_interval">ZMQ_RECOVERY_IVL: Set multicast recovery interval</h3>
<div class="paragraph"><p>The <em>ZMQ_RECOVERY_IVL</em> option shall set the recovery interval for multicast
transports using the specified <em>socket</em>. The recovery interval determines the
maximum time in milliseconds that a receiver can be absent from a multicast
group before unrecoverable data loss will occur.</p></div>
<div class="admonitionblock">
<table><tr>
<td class="icon">
<div class="title">Caution</div>
</td>
<td class="content">Exercise care when setting large recovery intervals as the data
needed for recovery will be held in memory. For example, a 1 minute recovery
interval at a data rate of 1Gbps requires a 7GB in-memory buffer.</td>
</tr></table>
</div>
<div class="hdlist"><table>
<tr>
<td class="hdlist1">
Option value type
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
int
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Option value unit
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
milliseconds
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Default value
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
10000
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Applicable socket types
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
all, when using multicast transports
</p>
</td>
</tr>
</table></div>
</div>
<div class="sect2">
<h3 id="_zmq_req_correlate_match_replies_with_requests">ZMQ_REQ_CORRELATE: match replies with requests</h3>
<div class="paragraph"><p>The default behaviour of REQ sockets is to rely on the ordering of messages to
match requests and responses and that is usually sufficient. When this option
is set to 1, the REQ socket will prefix outgoing messages with an extra frame
containing a request id. That means the full message is (request id, 0,
user frames&#8230;). The REQ socket will discard all incoming messages that don&#8217;t
begin with these two frames.</p></div>
<div class="hdlist"><table>
<tr>
<td class="hdlist1">
Option value type
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
int
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Option value unit
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
0, 1
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Default value
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
0
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Applicable socket types
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
ZMQ_REQ
</p>
</td>
</tr>
</table></div>
</div>
<div class="sect2">
<h3 id="_zmq_req_relaxed_relax_strict_alternation_between_request_and_reply">ZMQ_REQ_RELAXED: relax strict alternation between request and reply</h3>
<div class="paragraph"><p>By default, a REQ socket does not allow initiating a new request with
<em>zmq_send(3)</em> until the reply to the previous one has been received.
When set to 1, sending another message is allowed and previous replies will
be discarded if any. The request-reply state machine is reset and a new
request is sent to the next available peer.</p></div>
<div class="paragraph"><p>If set to 1, also enable ZMQ_REQ_CORRELATE to ensure correct matching of
requests and replies. Otherwise a late reply to an aborted request can be
reported as the reply to the superseding request.</p></div>
<div class="hdlist"><table>
<tr>
<td class="hdlist1">
Option value type
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
int
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Option value unit
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
0, 1
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Default value
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
0
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Applicable socket types
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
ZMQ_REQ
</p>
</td>
</tr>
</table></div>
</div>
<div class="sect2">
<h3 id="_zmq_router_handover_handle_duplicate_client_routing_ids_on_router_sockets">ZMQ_ROUTER_HANDOVER: handle duplicate client routing ids on ROUTER sockets</h3>
<div class="paragraph"><p>If two clients use the same routing id when connecting to a ROUTER, the
results shall depend on the ZMQ_ROUTER_HANDOVER option setting. If that
is not set (or set to the default of zero), the ROUTER socket shall reject
clients trying to connect with an already-used routing id. If that option
is set to 1, the ROUTER socket shall hand-over the connection to the new
client and disconnect the existing one.</p></div>
<div class="hdlist"><table>
<tr>
<td class="hdlist1">
Option value type
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
int
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Option value unit
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
0, 1
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Default value
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
0
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Applicable socket types
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
ZMQ_ROUTER
</p>
</td>
</tr>
</table></div>
</div>
<div class="sect2">
<h3 id="_zmq_router_mandatory_accept_only_routable_messages_on_router_sockets">ZMQ_ROUTER_MANDATORY: accept only routable messages on ROUTER sockets</h3>
<div class="paragraph"><p>Sets the ROUTER socket behaviour when an unroutable message is encountered. A
value of <code>0</code> is the default and discards the message silently when it cannot be
routed or the peers SNDHWM is reached.  A value of <code>1</code> returns an
<em>EHOSTUNREACH</em> error code if the message cannot be routed or <em>EAGAIN</em> error
code if the SNDHWM is reached and ZMQ_DONTWAIT was used. Without ZMQ_DONTWAIT
it will block until the SNDTIMEO is reached or a spot in the send queue opens
up.</p></div>
<div class="paragraph"><p>When ZMQ_ROUTER_MANDATORY is set to <code>1</code>, <em>ZMQ_POLLOUT</em> events will be generated
if one or more messages can be sent to at least one of the peers. If
ZMQ_ROUTER_MANDATORY is set to <code>0</code>, the socket will generate a <em>ZMQ_POLLOUT</em>
event on every call to <em>zmq_poll</em> resp. <em>zmq_poller_wait_all</em>.</p></div>
<div class="hdlist"><table>
<tr>
<td class="hdlist1">
Option value type
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
int
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Option value unit
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
0, 1
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Default value
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
0
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Applicable socket types
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
ZMQ_ROUTER
</p>
</td>
</tr>
</table></div>
</div>
<div class="sect2">
<h3 id="_zmq_router_raw_switch_router_socket_to_raw_mode">ZMQ_ROUTER_RAW: switch ROUTER socket to raw mode</h3>
<div class="paragraph"><p>Sets the raw mode on the ROUTER, when set to 1. When the ROUTER socket is in
raw mode, and when using the tcp:// transport, it will read and write TCP data
without ØMQ framing. This lets ØMQ applications talk to non-ØMQ applications.
When using raw mode, you cannot set explicit identities, and the ZMQ_SNDMORE
flag is ignored when sending data messages. In raw mode you can close a specific
connection by sending it a zero-length message (following the routing id frame).</p></div>
<div class="admonitionblock">
<table><tr>
<td class="icon">
<div class="title">Note</div>
</td>
<td class="content">This option is deprecated, please use ZMQ_STREAM sockets instead.</td>
</tr></table>
</div>
<div class="hdlist"><table>
<tr>
<td class="hdlist1">
Option value type
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
int
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Option value unit
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
0, 1
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Default value
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
0
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Applicable socket types
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
ZMQ_ROUTER
</p>
</td>
</tr>
</table></div>
</div>
<div class="sect2">
<h3 id="_zmq_routing_id_set_socket_routing_id">ZMQ_ROUTING_ID: Set socket routing id</h3>
<div class="paragraph"><p>The <em>ZMQ_ROUTING_ID</em> option shall set the routing id of the specified <em>socket</em>
when connecting to a ROUTER socket.</p></div>
<div class="paragraph"><p>A routing id must be at least one byte and at most 255 bytes long. Identities
starting with a zero byte are reserved for use by the ØMQ infrastructure.</p></div>
<div class="paragraph"><p>If two clients use the same routing id when connecting to a ROUTER, the
results shall depend on the ZMQ_ROUTER_HANDOVER option setting. If that
is not set (or set to the default of zero), the ROUTER socket shall reject
clients trying to connect with an already-used routing id. If that option
is set to 1, the ROUTER socket shall hand-over the connection to the new
client and disconnect the existing one.</p></div>
<div class="hdlist"><table>
<tr>
<td class="hdlist1">
Option value type
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
binary data
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Option value unit
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
N/A
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Default value
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
NULL
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Applicable socket types
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
ZMQ_REQ, ZMQ_REP, ZMQ_ROUTER, ZMQ_DEALER.
</p>
</td>
</tr>
</table></div>
</div>
<div class="sect2">
<h3 id="_zmq_sndbuf_set_kernel_transmit_buffer_size">ZMQ_SNDBUF: Set kernel transmit buffer size</h3>
<div class="paragraph"><p>The <em>ZMQ_SNDBUF</em> option shall set the underlying kernel transmit buffer size
for the <em>socket</em> to the specified size in bytes.  A value of -1 means leave
the OS default unchanged. For details please refer to your operating system
documentation for the <em>SO_SNDBUF</em> socket option.</p></div>
<div class="hdlist"><table>
<tr>
<td class="hdlist1">
Option value type
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
int
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Option value unit
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
bytes
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Default value
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
-1
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Applicable socket types
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
all
</p>
</td>
</tr>
</table></div>
</div>
<div class="sect2">
<h3 id="_zmq_sndhwm_set_high_water_mark_for_outbound_messages">ZMQ_SNDHWM: Set high water mark for outbound messages</h3>
<div class="paragraph"><p>The <em>ZMQ_SNDHWM</em> option shall set the high water mark for outbound messages on
the specified <em>socket</em>. The high water mark is a hard limit on the maximum
number of outstanding messages ØMQ shall queue in memory for any single peer
that the specified <em>socket</em> is communicating with. A value of zero means no
limit.</p></div>
<div class="paragraph"><p>If this limit has been reached the socket shall enter an exceptional state and
depending on the socket type, ØMQ shall take appropriate action such as
blocking or dropping sent messages. Refer to the individual socket descriptions
in <a href="zmq_socket.html">zmq_socket(3)</a> for details on the exact action taken for each socket
type.</p></div>
<div class="admonitionblock">
<table><tr>
<td class="icon">
<div class="title">Note</div>
</td>
<td class="content">ØMQ does not guarantee that the socket will accept as many as ZMQ_SNDHWM
messages, and the actual limit may be as much as 90% lower depending on the
flow of messages on the socket. The socket may even be able to accept more messages
than the ZMQ_SNDHWM threshold; a notable example is for sockets using TCP transport;
see <a href="zmq_tcp.html">zmq_tcp(7)</a>.</td>
</tr></table>
</div>
<div class="hdlist"><table>
<tr>
<td class="hdlist1">
Option value type
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
int
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Option value unit
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
messages
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Default value
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
1000
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Applicable socket types
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
all
</p>
</td>
</tr>
</table></div>
</div>
<div class="sect2">
<h3 id="_zmq_sndtimeo_maximum_time_before_a_send_operation_returns_with_eagain">ZMQ_SNDTIMEO: Maximum time before a send operation returns with EAGAIN</h3>
<div class="paragraph"><p>Sets the timeout for send operation on the socket. If the value is <code>0</code>,
<em>zmq_send(3)</em> will return immediately, with a EAGAIN error if the message
cannot be sent. If the value is <code>-1</code>, it will block until the message is sent.
For all other values, it will try to send the message for that amount of time
before returning with an EAGAIN error.</p></div>
<div class="hdlist"><table>
<tr>
<td class="hdlist1">
Option value type
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
int
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Option value unit
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
milliseconds
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Default value
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
-1 (infinite)
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Applicable socket types
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
all
</p>
</td>
</tr>
</table></div>
</div>
<div class="sect2">
<h3 id="_zmq_socks_proxy_set_socks5_proxy_address">ZMQ_SOCKS_PROXY: Set SOCKS5 proxy address</h3>
<div class="paragraph"><p>Sets the SOCKS5 proxy address that shall be used by the socket for the TCP
connection(s). Supported authentication methods are: no authentication
or basic authentication when setup with ZMQ_SOCKS_USERNAME. If the endpoints
are domain names instead of addresses they shall not be resolved and they
shall be forwarded unchanged to the SOCKS proxy service in the client
connection request message (address type 0x03 domain name).</p></div>
<div class="hdlist"><table>
<tr>
<td class="hdlist1">
Option value type
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
character string
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Option value unit
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
N/A
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Default value
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
not set
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Applicable socket types
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
all, when using TCP transport
</p>
</td>
</tr>
</table></div>
</div>
<div class="sect2">
<h3 id="_zmq_socks_username_set_socks_username_and_select_basic_authentication">ZMQ_SOCKS_USERNAME: Set SOCKS username and select basic authentication</h3>
<div class="paragraph"><p>Sets the username for authenticated connection to the SOCKS5 proxy.
If you set this to a non-null and non-empty value, the authentication
method used for the SOCKS5 connection shall be basic authentication.
In this case, use ZMQ_SOCKS_PASSWORD option in order to set the password.
If you set this to a null value or empty value, the authentication method
shall be no authentication, the default.</p></div>
<div class="hdlist"><table>
<tr>
<td class="hdlist1">
Option value type
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
character string
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Option value unit
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
N/A
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Default value
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
not set
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Applicable socket types
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
all, when using TCP transport
</p>
</td>
</tr>
</table></div>
</div>
<div class="sect2">
<h3 id="_zmq_socks_password_set_socks_basic_authentication_password">ZMQ_SOCKS_PASSWORD: Set SOCKS basic authentication password</h3>
<div class="paragraph"><p>Sets the password for authenticating to the SOCKS5 proxy server.
This is used only when the SOCKS5 authentication method has been
set to basic authentication through the ZMQ_SOCKS_USERNAME option.
Setting this to a null value (the default) is equivalent to an
empty password string.</p></div>
<div class="hdlist"><table>
<tr>
<td class="hdlist1">
Option value type
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
character string
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Option value unit
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
N/A
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Default value
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
not set
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Applicable socket types
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
all, when using TCP transport
</p>
</td>
</tr>
</table></div>
</div>
<div class="sect2">
<h3 id="_zmq_stream_notify_send_connect_and_disconnect_notifications">ZMQ_STREAM_NOTIFY: send connect and disconnect notifications</h3>
<div class="paragraph"><p>Enables connect and disconnect notifications on a STREAM socket, when set
to 1. When notifications are enabled, the socket delivers a zero-length
message when a peer connects or disconnects.</p></div>
<div class="hdlist"><table>
<tr>
<td class="hdlist1">
Option value type
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
int
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Option value unit
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
0, 1
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Default value
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
1
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Applicable socket types
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
ZMQ_STREAM
</p>
</td>
</tr>
</table></div>
</div>
<div class="sect2">
<h3 id="_zmq_subscribe_establish_message_filter">ZMQ_SUBSCRIBE: Establish message filter</h3>
<div class="paragraph"><p>The <em>ZMQ_SUBSCRIBE</em> option shall establish a new message filter on a <em>ZMQ_SUB</em>
socket. Newly created <em>ZMQ_SUB</em> sockets shall filter out all incoming messages,
therefore you should call this option to establish an initial message filter.</p></div>
<div class="paragraph"><p>An empty <em>option_value</em> of length zero shall subscribe to all incoming
messages. A non-empty <em>option_value</em> shall subscribe to all messages beginning
with the specified prefix. Multiple filters may be attached to a single
<em>ZMQ_SUB</em> socket, in which case a message shall be accepted if it matches at
least one filter.</p></div>
<div class="hdlist"><table>
<tr>
<td class="hdlist1">
Option value type
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
binary data
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Option value unit
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
N/A
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Default value
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
N/A
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Applicable socket types
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
ZMQ_SUB
</p>
</td>
</tr>
</table></div>
</div>
<div class="sect2">
<h3 id="_zmq_tcp_keepalive_override_so_keepalive_socket_option">ZMQ_TCP_KEEPALIVE: Override SO_KEEPALIVE socket option</h3>
<div class="paragraph"><p>Override <em>SO_KEEPALIVE</em> socket option (where supported by OS).
The default value of <code>-1</code> means to skip any overrides and leave it to OS default.</p></div>
<div class="hdlist"><table>
<tr>
<td class="hdlist1">
Option value type
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
int
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Option value unit
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
-1,0,1
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Default value
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
-1 (leave to OS default)
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Applicable socket types
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
all, when using TCP transports.
</p>
</td>
</tr>
</table></div>
</div>
<div class="sect2">
<h3 id="_zmq_tcp_keepalive_cnt_override_tcp_keepcnt_socket_option">ZMQ_TCP_KEEPALIVE_CNT: Override TCP_KEEPCNT socket option</h3>
<div class="paragraph"><p>Override <em>TCP_KEEPCNT</em> socket option (where supported by OS). The default
value of <code>-1</code> means to skip any overrides and leave it to OS default.</p></div>
<div class="hdlist"><table>
<tr>
<td class="hdlist1">
Option value type
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
int
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Option value unit
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
-1,&gt;0
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Default value
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
-1 (leave to OS default)
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Applicable socket types
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
all, when using TCP transports.
</p>
</td>
</tr>
</table></div>
</div>
<div class="sect2">
<h3 id="_zmq_tcp_keepalive_idle_override_tcp_keepidle_or_tcp_keepalive_on_some_os">ZMQ_TCP_KEEPALIVE_IDLE: Override TCP_KEEPIDLE (or TCP_KEEPALIVE on some OS)</h3>
<div class="paragraph"><p>Override <em>TCP_KEEPIDLE</em> (or <em>TCP_KEEPALIVE</em> on some OS) socket option (where
supported by OS). The default value of <code>-1</code> means to skip any overrides and
leave it to OS default.</p></div>
<div class="hdlist"><table>
<tr>
<td class="hdlist1">
Option value type
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
int
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Option value unit
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
-1,&gt;0
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Default value
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
-1 (leave to OS default)
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Applicable socket types
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
all, when using TCP transports.
</p>
</td>
</tr>
</table></div>
</div>
<div class="sect2">
<h3 id="_zmq_tcp_keepalive_intvl_override_tcp_keepintvl_socket_option">ZMQ_TCP_KEEPALIVE_INTVL: Override TCP_KEEPINTVL socket option</h3>
<div class="paragraph"><p>Override <em>TCP_KEEPINTVL</em> socket option(where supported by OS). The default
value of <code>-1</code> means to skip any overrides and leave it to OS default.</p></div>
<div class="hdlist"><table>
<tr>
<td class="hdlist1">
Option value type
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
int
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Option value unit
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
-1,&gt;0
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Default value
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
-1 (leave to OS default)
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Applicable socket types
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
all, when using TCP transports.
</p>
</td>
</tr>
</table></div>
</div>
<div class="sect2">
<h3 id="_zmq_tcp_maxrt_set_tcp_maximum_retransmit_timeout">ZMQ_TCP_MAXRT: Set TCP Maximum Retransmit Timeout</h3>
<div class="paragraph"><p>On OSes where it is supported, sets how long before an unacknowledged TCP
retransmit times out. The system normally attempts many TCP retransmits
following an exponential backoff strategy. This means that after a network
outage, it may take a long time before the session can be re-established.
Setting this option allows the timeout to happen at a shorter interval.</p></div>
<div class="hdlist"><table>
<tr>
<td class="hdlist1">
Option value type
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
int
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Option value unit
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
milliseconds
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Default value
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
0 (leave to OS default)
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Applicable socket types
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
all, when using TCP transports.
</p>
</td>
</tr>
</table></div>
</div>
<div class="sect2">
<h3 id="_zmq_tos_set_the_type_of_service_on_socket">ZMQ_TOS: Set the Type-of-Service on socket</h3>
<div class="paragraph"><p>Sets the ToS fields (Differentiated services (DS) and Explicit Congestion
Notification (ECN) field of the IP header. The ToS field is typically used
to specify a packets priority. The availability of this option is dependent
on intermediate network equipment that inspect the ToS field and provide a
path for low-delay, high-throughput, highly-reliable service, etc.</p></div>
<div class="hdlist"><table>
<tr>
<td class="hdlist1">
Option value type
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
int
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Option value unit
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
&gt;0
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Default value
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
0
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Applicable socket types
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
all, only for connection-oriented transports
</p>
</td>
</tr>
</table></div>
</div>
<div class="sect2">
<h3 id="_zmq_unsubscribe_remove_message_filter">ZMQ_UNSUBSCRIBE: Remove message filter</h3>
<div class="paragraph"><p>The <em>ZMQ_UNSUBSCRIBE</em> option shall remove an existing message filter on a
<em>ZMQ_SUB</em> socket. The filter specified must match an existing filter previously
established with the <em>ZMQ_SUBSCRIBE</em> option. If the socket has several
instances of the same filter attached the <em>ZMQ_UNSUBSCRIBE</em> option shall remove
only one instance, leaving the rest in place and functional.</p></div>
<div class="hdlist"><table>
<tr>
<td class="hdlist1">
Option value type
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
binary data
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Option value unit
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
N/A
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Default value
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
N/A
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Applicable socket types
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
ZMQ_SUB
</p>
</td>
</tr>
</table></div>
</div>
<div class="sect2">
<h3 id="_zmq_xpub_verbose_pass_duplicate_subscribe_messages_on_xpub_socket">ZMQ_XPUB_VERBOSE: pass duplicate subscribe messages on XPUB socket</h3>
<div class="paragraph"><p>Sets the <em>XPUB</em> socket behaviour on new duplicated subscriptions. If enabled,
the socket passes all subscribe messages to the caller. If disabled,
only the first subscription to each filter will be passed. The default is 0
(disabled).</p></div>
<div class="hdlist"><table>
<tr>
<td class="hdlist1">
Option value type
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
int
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Option value unit
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
0, 1
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Default value
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
0
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Applicable socket types
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
ZMQ_XPUB
</p>
</td>
</tr>
</table></div>
</div>
<div class="sect2">
<h3 id="_zmq_xpub_verboser_pass_duplicate_subscribe_and_unsubscribe_messages_on_xpub_socket">ZMQ_XPUB_VERBOSER: pass duplicate subscribe and unsubscribe messages on XPUB socket</h3>
<div class="paragraph"><p>Sets the <em>XPUB</em> socket behaviour on new duplicated subscriptions and
unsubscriptions. If enabled, the socket passes all subscribe and unsubscribe
messages to the caller. If disabled, only the first subscription to each filter and
the last unsubscription from each filter will be passed. The default is 0
(disabled).</p></div>
<div class="hdlist"><table>
<tr>
<td class="hdlist1">
Option value type
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
int
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Option value unit
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
0, 1
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Default value
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
0
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Applicable socket types
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
ZMQ_XPUB
</p>
</td>
</tr>
</table></div>
</div>
<div class="sect2">
<h3 id="_zmq_xpub_manual_change_the_subscription_handling_to_manual">ZMQ_XPUB_MANUAL: change the subscription handling to manual</h3>
<div class="paragraph"><p>Sets the <em>XPUB</em> socket subscription handling mode manual/automatic.
A value of <em>0</em> is the default and subscription requests will be handled automatically.
A value of <em>1</em> will change the subscription requests handling to manual,
with manual mode subscription requests are not added to the subscription list.
To add subscription the user need to call setsockopt with ZMQ_SUBSCRIBE on XPUB socket.</p></div>
<div class="hdlist"><table>
<tr>
<td class="hdlist1">
Option value type
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
int
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Option value unit
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
0, 1
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Default value
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
0
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Applicable socket types
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
ZMQ_XPUB
</p>
</td>
</tr>
</table></div>
</div>
<div class="sect2">
<h3 id="_zmq_xpub_manual_last_value_change_the_subscription_handling_to_manual">ZMQ_XPUB_MANUAL_LAST_VALUE: change the subscription handling to manual</h3>
<div class="paragraph"><p>This option is similar to ZMQ_XPUB_MANUAL.
The difference is that ZMQ_XPUB_MANUAL_LAST_VALUE changes the <em>XPUB</em> socket
behaviour to send the first message to the last subscriber after the socket
receives a subscription and call setsockopt with ZMQ_SUBSCRIBE on <em>XPUB</em> socket.
This prevents duplicated messages when using last value caching(LVC).</p></div>
<div class="admonitionblock">
<table><tr>
<td class="icon">
<div class="title">Note</div>
</td>
<td class="content">in DRAFT state, not yet available in stable releases.</td>
</tr></table>
</div>
<div class="hdlist"><table>
<tr>
<td class="hdlist1">
Option value type
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
int
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Option value unit
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
0, 1
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Default value
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
0
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Applicable socket types
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
ZMQ_XPUB
</p>
</td>
</tr>
</table></div>
</div>
<div class="sect2">
<h3 id="_zmq_xpub_nodrop_do_not_silently_drop_messages_if_sendhwm_is_reached">ZMQ_XPUB_NODROP: do not silently drop messages if SENDHWM is reached</h3>
<div class="paragraph"><p>Sets the <em>XPUB</em> socket behaviour to return error EAGAIN if SENDHWM is
reached and the message could not be send.</p></div>
<div class="paragraph"><p>A value of <code>0</code> is the default and drops the message silently when the peers
SNDHWM is reached.  A value of <code>1</code> returns an <em>EAGAIN</em> error code if the
SNDHWM is reached and ZMQ_DONTWAIT was used.</p></div>
<div class="hdlist"><table>
<tr>
<td class="hdlist1">
Option value type
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
int
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Option value unit
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
0, 1
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Default value
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
0
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Applicable socket types
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
ZMQ_XPUB, ZMQ_PUB
</p>
</td>
</tr>
</table></div>
</div>
<div class="sect2">
<h3 id="_zmq_xpub_welcome_msg_set_welcome_message_that_will_be_received_by_subscriber_when_connecting">ZMQ_XPUB_WELCOME_MSG: set welcome message that will be received by subscriber when connecting</h3>
<div class="paragraph"><p>Sets a welcome message the will be recieved by subscriber when connecting.
Subscriber must subscribe to the Welcome message before connecting.
Welcome message will also be sent on reconnecting.
For welcome message to work well user must poll on incoming subscription messages on the XPUB socket and handle them.</p></div>
<div class="paragraph"><p>Use NULL and length of zero to disable welcome message.</p></div>
<div class="hdlist"><table>
<tr>
<td class="hdlist1">
Option value type
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
binary data
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Option value unit
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
N/A
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Default value
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
NULL
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Applicable socket types
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
ZMQ_XPUB
</p>
</td>
</tr>
</table></div>
</div>
<div class="sect2">
<h3 id="_zmq_zap_domain_set_rfc_27_authentication_domain">ZMQ_ZAP_DOMAIN: Set RFC 27 authentication domain</h3>
<div class="paragraph"><p>Sets the domain for ZAP (ZMQ RFC 27) authentication. A ZAP domain must be
specified to enable authentication. When the ZAP domain is empty, which is
the default, ZAP authentication is disabled. This is not compatible with
previous versions of libzmq, so it can be controlled by ZMQ_ZAP_ENFORCE_DOMAIN
which for now is disabled by default.
See <a href="http://rfc.zeromq.org/spec:27">http://rfc.zeromq.org/spec:27</a> for more details.</p></div>
<div class="hdlist"><table>
<tr>
<td class="hdlist1">
Option value type
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
character string
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Option value unit
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
N/A
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Default value
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
empty
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Applicable socket types
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
all, when using TCP transport
</p>
</td>
</tr>
</table></div>
</div>
<div class="sect2">
<h3 id="_zmq_zap_enforce_domain_set_zap_domain_handling_to_strictly_adhere_the_rfc">ZMQ_ZAP_ENFORCE_DOMAIN: Set ZAP domain handling to strictly adhere the RFC</h3>
<div class="paragraph"><p>The ZAP (ZMQ RFC 27) authentication protocol specifies that a domain must
always be set. Older versions of libzmq did not follow the spec and allowed
an empty domain to be set.
This option can be used to enabled or disable the stricter, backward
incompatible behaviour. For now it is disabled by default, but in a future
version it will be enabled by default.</p></div>
<div class="hdlist"><table>
<tr>
<td class="hdlist1">
Option value type
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
int
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Option value unit
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
0, 1
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Default value
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
0
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Applicable socket types
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
all, when using ZAP
</p>
</td>
</tr>
</table></div>
</div>
<div class="sect2">
<h3 id="_zmq_tcp_accept_filter_assign_filters_to_allow_new_tcp_connections">ZMQ_TCP_ACCEPT_FILTER: Assign filters to allow new TCP connections</h3>
<div class="paragraph"><p>Assign an arbitrary number of filters that will be applied for each new TCP
transport connection on a listening socket. If no filters are applied, then
the TCP transport allows connections from any IP address. If at least one
filter is applied then new connection source ip should be matched. To clear
all filters call zmq_setsockopt(socket, ZMQ_TCP_ACCEPT_FILTER, NULL, 0).
Filter is a null-terminated string with ipv6 or ipv4 CIDR.</p></div>
<div class="admonitionblock">
<table><tr>
<td class="icon">
<div class="title">Note</div>
</td>
<td class="content">This option is deprecated, please use authentication via the ZAP API
and IP address whitelisting / blacklisting.</td>
</tr></table>
</div>
<div class="hdlist"><table>
<tr>
<td class="hdlist1">
Option value type
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
binary data
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Option value unit
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
N/A
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Default value
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
no filters (allow from all)
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Applicable socket types
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
all listening sockets, when using TCP transports.
</p>
</td>
</tr>
</table></div>
</div>
<div class="sect2">
<h3 id="_zmq_ipc_filter_gid_assign_group_id_filters_to_allow_new_ipc_connections">ZMQ_IPC_FILTER_GID: Assign group ID filters to allow new IPC connections</h3>
<div class="paragraph"><p>Assign an arbitrary number of filters that will be applied for each new IPC
transport connection on a listening socket. If no IPC filters are applied, then
the IPC transport allows connections from any process. If at least one UID,
GID, or PID filter is applied then new connection credentials should be
matched. To clear all GID filters call zmq_setsockopt(socket,
ZMQ_IPC_FILTER_GID, NULL, 0).</p></div>
<div class="admonitionblock">
<table><tr>
<td class="icon">
<div class="title">Note</div>
</td>
<td class="content">GID filters are only available on platforms supporting SO_PEERCRED or
LOCAL_PEERCRED socket options (currently only Linux and later versions of
OS X).</td>
</tr></table>
</div>
<div class="admonitionblock">
<table><tr>
<td class="icon">
<div class="title">Note</div>
</td>
<td class="content">This option is deprecated, please use authentication via the ZAP API
and IPC whitelisting / blacklisting.</td>
</tr></table>
</div>
<div class="hdlist"><table>
<tr>
<td class="hdlist1">
Option value type
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
gid_t
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Option value unit
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
N/A
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Default value
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
no filters (allow from all)
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Applicable socket types
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
all listening sockets, when using IPC transports.
</p>
</td>
</tr>
</table></div>
</div>
<div class="sect2">
<h3 id="_zmq_ipc_filter_pid_assign_process_id_filters_to_allow_new_ipc_connections">ZMQ_IPC_FILTER_PID: Assign process ID filters to allow new IPC connections</h3>
<div class="paragraph"><p>Assign an arbitrary number of filters that will be applied for each new IPC
transport connection on a listening socket. If no IPC filters are applied, then
the IPC transport allows connections from any process. If at least one UID,
GID, or PID filter is applied then new connection credentials should be
matched. To clear all PID filters call zmq_setsockopt(socket,
ZMQ_IPC_FILTER_PID, NULL, 0).</p></div>
<div class="admonitionblock">
<table><tr>
<td class="icon">
<div class="title">Note</div>
</td>
<td class="content">PID filters are only available on platforms supporting the SO_PEERCRED
socket option (currently only Linux).</td>
</tr></table>
</div>
<div class="admonitionblock">
<table><tr>
<td class="icon">
<div class="title">Note</div>
</td>
<td class="content">This option is deprecated, please use authentication via the ZAP API
and IPC whitelisting / blacklisting.</td>
</tr></table>
</div>
<div class="hdlist"><table>
<tr>
<td class="hdlist1">
Option value type
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
pid_t
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Option value unit
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
N/A
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Default value
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
no filters (allow from all)
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Applicable socket types
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
all listening sockets, when using IPC transports.
</p>
</td>
</tr>
</table></div>
</div>
<div class="sect2">
<h3 id="_zmq_ipc_filter_uid_assign_user_id_filters_to_allow_new_ipc_connections">ZMQ_IPC_FILTER_UID: Assign user ID filters to allow new IPC connections</h3>
<div class="paragraph"><p>Assign an arbitrary number of filters that will be applied for each new IPC
transport connection on a listening socket. If no IPC filters are applied, then
the IPC transport allows connections from any process. If at least one UID,
GID, or PID filter is applied then new connection credentials should be
matched. To clear all UID filters call zmq_setsockopt(socket,
ZMQ_IPC_FILTER_UID, NULL, 0).</p></div>
<div class="admonitionblock">
<table><tr>
<td class="icon">
<div class="title">Note</div>
</td>
<td class="content">UID filters are only available on platforms supporting SO_PEERCRED or
LOCAL_PEERCRED socket options (currently only Linux and later versions of
OS X).</td>
</tr></table>
</div>
<div class="admonitionblock">
<table><tr>
<td class="icon">
<div class="title">Note</div>
</td>
<td class="content">This option is deprecated, please use authentication via the ZAP API
and IPC whitelisting / blacklisting.</td>
</tr></table>
</div>
<div class="hdlist"><table>
<tr>
<td class="hdlist1">
Option value type
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
uid_t
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Option value unit
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
N/A
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Default value
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
no filters (allow from all)
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Applicable socket types
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
all listening sockets, when using IPC transports.
</p>
</td>
</tr>
</table></div>
</div>
<div class="sect2">
<h3 id="_zmq_ipv4only_use_ipv4_only_on_socket">ZMQ_IPV4ONLY: Use IPv4-only on socket</h3>
<div class="paragraph"><p>Set the IPv4-only option for the socket. This option is deprecated.
Please use the ZMQ_IPV6 option.</p></div>
<div class="hdlist"><table>
<tr>
<td class="hdlist1">
Option value type
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
int
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Option value unit
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
boolean
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Default value
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
1 (true)
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Applicable socket types
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
all, when using TCP transports.
</p>
</td>
</tr>
</table></div>
</div>
<div class="sect2">
<h3 id="_zmq_vmci_buffer_size_set_buffer_size_of_the_vmci_socket">ZMQ_VMCI_BUFFER_SIZE: Set buffer size of the VMCI socket</h3>
<div class="paragraph"><p>The <code>ZMQ_VMCI_BUFFER_SIZE</code> option shall set the size of the underlying
buffer for the socket. Used during negotiation before the connection is established.</p></div>
<div class="hdlist"><table>
<tr>
<td class="hdlist1">
Option value type
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
uint64_t
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Option value unit
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
bytes
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Default value
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
65546
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Applicable socket types
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
all, when using VMCI transport
</p>
</td>
</tr>
</table></div>
</div>
<div class="sect2">
<h3 id="_zmq_vmci_buffer_min_size_set_min_buffer_size_of_the_vmci_socket">ZMQ_VMCI_BUFFER_MIN_SIZE: Set min buffer size of the VMCI socket</h3>
<div class="paragraph"><p>The <code>ZMQ_VMCI_BUFFER_MIN_SIZE</code> option shall set the min size of the underlying
buffer for the socket. Used during negotiation before the connection is established.</p></div>
<div class="hdlist"><table>
<tr>
<td class="hdlist1">
Option value type
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
uint64_t
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Option value unit
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
bytes
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Default value
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
128
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Applicable socket types
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
all, when using VMCI transport
</p>
</td>
</tr>
</table></div>
</div>
<div class="sect2">
<h3 id="_zmq_vmci_buffer_max_size_set_max_buffer_size_of_the_vmci_socket">ZMQ_VMCI_BUFFER_MAX_SIZE: Set max buffer size of the VMCI socket</h3>
<div class="paragraph"><p>The <code>ZMQ_VMCI_BUFFER_MAX_SIZE</code> option shall set the max size of the underlying
buffer for the socket. Used during negotiation before the connection is established.</p></div>
<div class="hdlist"><table>
<tr>
<td class="hdlist1">
Option value type
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
uint64_t
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Option value unit
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
bytes
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Default value
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
262144
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Applicable socket types
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
all, when using VMCI transport
</p>
</td>
</tr>
</table></div>
</div>
<div class="sect2">
<h3 id="_zmq_vmci_connect_timeout_set_connection_timeout_of_the_vmci_socket">ZMQ_VMCI_CONNECT_TIMEOUT: Set connection timeout of the VMCI socket</h3>
<div class="paragraph"><p>The <code>ZMQ_VMCI_CONNECT_TIMEOUT</code> option shall set connection timeout
for the socket.</p></div>
<div class="hdlist"><table>
<tr>
<td class="hdlist1">
Option value type
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
int
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Option value unit
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
milliseconds
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Default value
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
-1
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Applicable socket types
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
all, when using VMCI transport
</p>
</td>
</tr>
</table></div>
</div>
<div class="sect2">
<h3 id="_zmq_multicast_loop_control_multicast_local_loopback">ZMQ_MULTICAST_LOOP: Control multicast local loopback</h3>
<div class="paragraph"><p>For multicast UDP sender sockets this option sets whether the data
sent should be looped back on local listening sockets.</p></div>
<div class="hdlist"><table>
<tr>
<td class="hdlist1">
Option value type
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
int
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Option value unit
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
0, 1
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Default value
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
1
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Applicable socket types
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
ZMQ_RADIO, when using UDP multicast transport
</p>
</td>
</tr>
</table></div>
</div>
<div class="sect2">
<h3 id="_zmq_router_notify_send_connect_and_disconnect_notifications">ZMQ_ROUTER_NOTIFY: Send connect and disconnect notifications</h3>
<div class="paragraph"><p>Enable connect and disconnect notifications on a ROUTER socket.
When enabled, the socket delivers a zero-length message (with routing-id
as first frame) when a peer connects or disconnects. It&#8217;s possible
to notify both events for a peer by OR-ing the flag values. This option
only applies to stream oriented (tcp, ipc) transports.</p></div>
<div class="admonitionblock">
<table><tr>
<td class="icon">
<div class="title">Note</div>
</td>
<td class="content">in DRAFT state, not yet available in stable releases.</td>
</tr></table>
</div>
<div class="hdlist"><table>
<tr>
<td class="hdlist1">
Option value type
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
int
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Option value unit
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
0, ZMQ_NOTIFY_CONNECT, ZMQ_NOTIFY_DISCONNECT, ZMQ_NOTIFY_CONNECT | ZMQ_NOTIFY_DISCONNECT
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Default value
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
0
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Applicable socket types
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
ZMQ_ROUTER
</p>
</td>
</tr>
</table></div>
</div>
<div class="sect2">
<h3 id="_zmq_in_batch_size_maximal_receive_batch_size">ZMQ_IN_BATCH_SIZE: Maximal receive batch size</h3>
<div class="paragraph"><p>Sets the maximal amount of messages that can be received in a single
<em>recv</em> system call. WARNING: this option should almost never be changed.
The default has been chosen to offer the best compromise between latency and
throughtput. In the vast majority of cases, changing this option will result in
worst result if not outright breakages.</p></div>
<div class="paragraph"><p>Cannot be zero.</p></div>
<div class="admonitionblock">
<table><tr>
<td class="icon">
<div class="title">Note</div>
</td>
<td class="content">in DRAFT state, not yet available in stable releases.</td>
</tr></table>
</div>
<div class="hdlist"><table>
<tr>
<td class="hdlist1">
Option value type
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
int
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Option value unit
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
messages
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Default value
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
8192
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Applicable socket types
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
All, when using TCP, IPC, PGM or NORM transport.
</p>
</td>
</tr>
</table></div>
</div>
<div class="sect2">
<h3 id="_zmq_out_batch_size_maximal_send_batch_size">ZMQ_OUT_BATCH_SIZE: Maximal send batch size</h3>
<div class="paragraph"><p>Sets the maximal amount of messages that can be sent in a single
<em>send</em> system call. WARNING: this option should almost never be changed.
The default has been chosen to offer the best compromise between latency and
throughtput. In the vast majority of cases, changing this option will result in
worst result if not outright breakages.</p></div>
<div class="paragraph"><p>Cannot be zero.</p></div>
<div class="admonitionblock">
<table><tr>
<td class="icon">
<div class="title">Note</div>
</td>
<td class="content">in DRAFT state, not yet available in stable releases.</td>
</tr></table>
</div>
<div class="hdlist"><table>
<tr>
<td class="hdlist1">
Option value type
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
int
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Option value unit
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
messages
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Default value
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
8192
</p>
</td>
</tr>
<tr>
<td class="hdlist1">
Applicable socket types
<br />
</td>
<td class="hdlist2">
<p style="margin-top: 0;">
All, when using TCP, IPC, PGM or NORM transport.
</p>
</td>
</tr>
</table></div>
</div>
</div>
</div>
<div class="sect1">
<h2 id="_return_value">RETURN VALUE</h2>
<div class="sectionbody">
<div class="paragraph"><p>The <em>zmq_setsockopt()</em> function shall return zero if successful. Otherwise it
shall return <code>-1</code> and set <em>errno</em> to one of the values defined below.</p></div>
</div>
</div>
<div class="sect1">
<h2 id="_errors">ERRORS</h2>
<div class="sectionbody">
<div class="dlist"><dl>
<dt class="hdlist1">
<strong>EINVAL</strong>
</dt>
<dd>
<p>
The requested option <em>option_name</em> is unknown, or the requested <em>option_len</em> or
<em>option_value</em> is invalid.
</p>
</dd>
<dt class="hdlist1">
<strong>ETERM</strong>
</dt>
<dd>
<p>
The ØMQ <em>context</em> associated with the specified <em>socket</em> was terminated.
</p>
</dd>
<dt class="hdlist1">
<strong>ENOTSOCK</strong>
</dt>
<dd>
<p>
The provided <em>socket</em> was invalid.
</p>
</dd>
<dt class="hdlist1">
<strong>EINTR</strong>
</dt>
<dd>
<p>
The operation was interrupted by delivery of a signal.
</p>
</dd>
</dl></div>
</div>
</div>
<div class="sect1">
<h2 id="_example">EXAMPLE</h2>
<div class="sectionbody">
<div class="listingblock">
<div class="title">Subscribing to messages on a <em>ZMQ_SUB</em> socket</div>
<div class="content">
<pre><code>/* Subscribe to all messages */
rc = zmq_setsockopt (socket, ZMQ_SUBSCRIBE, "", 0);
assert (rc == 0);
/* Subscribe to messages prefixed with "ANIMALS.CATS" */
rc = zmq_setsockopt (socket, ZMQ_SUBSCRIBE, "ANIMALS.CATS", 12);</code></pre>
</div></div>
<div class="listingblock">
<div class="title">Setting I/O thread affinity</div>
<div class="content">
<pre><code>int64_t affinity;
/* Incoming connections on TCP port 5555 shall be handled by I/O thread 1 */
affinity = 1;
rc = zmq_setsockopt (socket, ZMQ_AFFINITY, &amp;affinity, sizeof (affinity));
assert (rc);
rc = zmq_bind (socket, "tcp://lo:5555");
assert (rc);
/* Incoming connections on TCP port 5556 shall be handled by I/O thread 2 */
affinity = 2;
rc = zmq_setsockopt (socket, ZMQ_AFFINITY, &amp;affinity, sizeof (affinity));
assert (rc);
rc = zmq_bind (socket, "tcp://lo:5556");
assert (rc);</code></pre>
</div></div>
</div>
</div>
<div class="sect1">
<h2 id="_see_also">SEE ALSO</h2>
<div class="sectionbody">
<div class="paragraph"><p><a href="zmq_getsockopt.html">zmq_getsockopt(3)</a>
<a href="zmq_socket.html">zmq_socket(3)</a>
<a href="zmq_plain.html">zmq_plain(7)</a>
<a href="zmq_curve.html">zmq_curve(7)</a>
<a href="zmq.html">zmq(7)</a></p></div>
</div>
</div>
<div class="sect1">
<h2 id="_authors">AUTHORS</h2>
<div class="sectionbody">
<div class="paragraph"><p>This page was written by the ØMQ community. To make a change please
read the ØMQ Contribution Policy at <a href="http://www.zeromq.org/docs:contributing">http://www.zeromq.org/docs:contributing</a>.</p></div>
</div>
</div>
</div>
<div id="footnotes"><hr /></div>
<div id="footer">
<div id="footer-text">
ØMQ 4.3.2<br />
Last updated 2019-07-08 16:19:27 UTC
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